Should we Cease and Desist?

Hello. I run a film review site and was recently sent a Cease and Desist letter from a filmmaker who did not get a favorable review for her film. She claimed since they have a copywrite on the name of the film we could not publicly slander it. We never attacked or maligned the filmmaker in our review, we just went through the review and explained to the readers why we didn't care for the film. It should be noted, the film was sent to us by the distributor of the film (a separate company) with no promise of a positive review. Are we covered under Freedom of Speech? Any advice would be helpful.